basisCurves.h

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//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef PXR_IMAGING_HD_ST_BASIS_CURVES_H
#define PXR_IMAGING_HD_ST_BASIS_CURVES_H

#include "pxr/pxr.h"
#include "pxr/imaging/hdSt/api.h"
#include "pxr/imaging/hd/version.h"
#include "pxr/imaging/hd/basisCurves.h"
#include "pxr/imaging/hd/drawingCoord.h"
#include "pxr/imaging/hd/enums.h"
#include "pxr/imaging/hd/perfLog.h"

#include "pxr/usd/sdf/path.h"
#include "pxr/base/vt/array.h"

#include <memory>

PXR_NAMESPACE_OPEN_SCOPE

class HdStDrawItem;
using HdSt_BasisCurvesTopologySharedPtr =
    std::shared_ptr<class HdSt_BasisCurvesTopology>;

/// \class HdStBasisCurves
///
/// A collection of curves using a particular basis.
///
/// Render mode is dependent on both the HdBasisCurvesGeomStyle, refinement 
/// level, and the authored primvars.
///
/// If style is set to HdBasisCurvesGeomStyleWire, the curves will always draw
/// as infinitely thin wires.  Cubic curves will be refined if complexity is
/// above 0, otherwise they draw the unrefined control points. (This may
/// provide a misleading representation for Catmull-Rom and Bspline curves.)
///
/// If style is set to HdBasisCurvesGeomStylePatch, the curves will draw as
/// patches ONLY if refinement level is above 0.  Otherwise, they draw
/// as the unrefined control points (see notes on HdBasisCurvesGeomStyleWire).
///
/// Curves rendered as patches may be rendered as ribbons or halftubes.
/// Curves with primvar authored normals will always render as ribbons.
/// Curves without primvar authored normals are assumed to be round and may be
/// rendered in one of three styles:
///   * if complexity is 1, a camera facing normal is used
///   * if complexity is 2, a fake "bumped" round normal is used
///   * if complexity is 3 or above, the patch is displaced into a half tube
/// We plan for future checkins will remove the need for the camera facing normal
/// mode, using the fake "bumped" round normal instead.
class HdStBasisCurves final: public HdBasisCurves {
public:
    HF_MALLOC_TAG_NEW("new HdStBasisCurves");

    HDST_API
    HdStBasisCurves(SdfPath const& id,
                    SdfPath const& instancerId = SdfPath());
    HDST_API
    virtual ~HdStBasisCurves();

    HDST_API
    virtual void Sync(HdSceneDelegate *delegate,
                      HdRenderParam   *renderParam,
                      HdDirtyBits     *dirtyBits,
                      TfToken const   &reprToken) override;

    HDST_API
    virtual HdDirtyBits GetInitialDirtyBitsMask() const override;

protected:
    HDST_API
    virtual void _InitRepr(TfToken const &reprToken,
                           HdDirtyBits *dirtyBits) override;

    HDST_API
    virtual HdDirtyBits _PropagateDirtyBits(HdDirtyBits bits) const override;

    void _UpdateRepr(HdSceneDelegate *sceneDelegate,
                     TfToken const &reprToken,
                     HdDirtyBits *dirtyBitsState);

    void _PopulateTopology(HdSceneDelegate *sceneDelegate,
                           HdStDrawItem *drawItem,
                           HdDirtyBits *dirtyBits,
                           const HdBasisCurvesReprDesc &desc);

    void _PopulateVertexPrimvars(HdSceneDelegate *sceneDelegate,
                                 HdStDrawItem *drawItem,
                                 HdDirtyBits *dirtyBits);

    void _PopulateElementPrimvars(HdSceneDelegate *sceneDelegate,
                                  HdStDrawItem *drawItem,
                                  HdDirtyBits *dirtyBits);


private:
    enum DrawingCoord {
        HullTopology = HdDrawingCoord::CustomSlotsBegin,
        PointsTopology,
        InstancePrimvar  // has to be at the very end
    };

    enum DirtyBits : HdDirtyBits {
        DirtyIndices        = HdChangeTracker::CustomBitsBegin,
        DirtyHullIndices    = (DirtyIndices       << 1),
        DirtyPointsIndices  = (DirtyHullIndices   << 1)
    };

    // When processing primvars, these will get set to if we determine that
    // we should do cubic basis interpolation on the normals and widths.
    // NOTE: I worry that it may be possible for these to get out of sync.
    // The right long term fix is likely to maintain proper separation between 
    // varying and vertex primvars throughout the HdSt rendering pipeline.
    bool _basisWidthInterpolation = false;
    bool _basisNormalInterpolation = false;

    bool _SupportsRefinement(int refineLevel);
    bool _SupportsUserWidths(HdStDrawItem* drawItem);
    bool _SupportsUserNormals(HdStDrawItem* drawItem);
    
    const TfToken& _GetMaterialTag(const HdRenderIndex &renderIndex) const;

    void _UpdateDrawItem(HdSceneDelegate *sceneDelegate,
                         HdStDrawItem *drawItem,
                         HdDirtyBits *dirtyBits,
                         const HdBasisCurvesReprDesc &desc);

    void _UpdateDrawItemGeometricShader(HdSceneDelegate *sceneDelegate,
                                        HdStDrawItem *drawItem,
                                        const HdBasisCurvesReprDesc &desc);
    
    void _UpdateShadersForAllReprs(HdSceneDelegate *sceneDelegate,
                                   bool updateMaterialShader,
                                   bool updateGeometricShader);


    HdSt_BasisCurvesTopologySharedPtr _topology;
    HdTopology::ID _topologyId;
    HdDirtyBits _customDirtyBitsInUse;
    int _refineLevel;  // XXX: could be moved into HdBasisCurveTopology.
};


PXR_NAMESPACE_CLOSE_SCOPE

#endif // PXR_IMAGING_HD_ST_BASIS_CURVES_H